Method of manufacturing fuse links



Jan, 3, 1950 J. L. YONKERS METHOD OF MANUFACTURING FUSE LINKS Filed March 21, 1946 55555550 w ...........-.V 555555555 55555555551. 55555555555555? E-E-E55!! M 4 65 ad aaa a add a a s INVENTOR. -John L. Yonkers WWW A fiorn e ys Patented Jan. 3, 1950 U N l TED S TATES (1) F FI CE METHOB) 9F MANUFACTURING FUSE LINKS John L; Yonkers, Northbrook, 11]., assigno'r to Joslyn Manufacturing and Supply Company; Chicago;- IlL; a; corporation of Illinois Appiication-March2-l, 194e, ScriaLNo. 656,043

1-2 Claims. I

The present invention relates to'a method of manufacturing fuse links, and more specifically to a method of manufacturing a sub-assemblycomprisinga plurality of serially arranged fusible elements such for example as are employed in a fuse link of the type disclosed and claimed inco-pending' Yonkers application Serial No. 637,528, filed l'J'ecember' 28, 1945, now Patent No. 2,453,396 issued Nov. 9, 1948, and assigned to the same a's'signee as the present application.

Fuse links of the general type disclosed in the above m'entioned copending application are emp'loy'ed-extensively in the protection of distribution circuits. When such fuse links have performed their protectivefunction they must be replaced by a new link. An-ordinary distribution system em.- pleys literally thousandsof such fuse links and it is very important, therefore; that they be relatively inexpensive; since otherwise the cost of prote'cting the distribution circuits becomes unreasonable; In order that fuse links may be manufactured so as to be sold at a relativelyiow cost it is essential thatthey be" produced on a mass production basis. Any manufacturing process which reduces thecost of assembly or manufacture becomes very important sinceif the'process saves a few cents on each fuse link it will save a. great'many dollars to the utility which emplbys' the resulting links in protecting its distribution circuits.

Quite recently fuse links of the type employing;

a plurality of fusible element's joined together by a meltable member such as solderyin which the fusible elements are ruptured in response to in stantaneous or very high currents of short dura tion such as short circuit currents while the melt-' able member joining the two fusible elements is adapted to fuse or melt in responseto long time overloads, have been extensivel-yemployed. The fuse link disclosed inthe above-mentioned copending application is an improved link of this type.

over older types of links, but have been relatively expensive to manufacture, primarily dueto the lack of a'rapid and inexpensive method of uniting ble elements for use in a fuse link, which method lends itself readil-yto mass production of the links on a low cost basis.

It is another object of the present invention to Fuse links of this improved form have very definite advantages from a functional standpoint" 2 provide for use in the manufacture of fuse links a' new and improved method of efficiently and rapidly miting a tubular conducting member with a wire-like conducting" element to form a fusible connection therebetween.

It is a still further object of the present invention to provide a new and improvedmethod of constructing a fuse link which greatly reduces the manufacturing cost as. well as the assembly time, and also permi'ts' the production of links having acceptably uniform operating characteristics on a mass production basis.

Further objects andi'adva'ntages of the present invention will become apparent as the following description'proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the present invention reference may be had to the accompanying drawings, in which:

Fig.1; is a sectional view of a fuse link including or-employing a sub-"assembly constructed in accordance with the present invention;

Fig. 2 is asectional view illustrating one step in the process of the present invention;

Fig. 3 is a sectional view illustrating 'stillanother step in the process of the'present invention;

Figs. land 5 are-sectional views illustrating still other steps in the process of the present invention;

Fig. 6 is an elevational view illustrating still another stepin the process of the present invention;

Fig. 7 is asectional View illustrating still an other-stepin the-processof the" present inven tion; and

Fig. 8 is anel'evatio'nal view similar to Fig. 6

illustrating the resulting sub-assembly createdin carrying out the process of the present invention; Althoughthe present invention applica' tion in the manufacture of various types of fuse linksg it 'is especially adaptable for the manufac-' ture of fuse linksof the improved form'disclosed'.

in the above-mentioned copendih'g Yonkers ap: pli'cation and accordingly the present invention is described in connection with the manufacture or a fusible element sub-assembly for use i'n the fuse link of the above mentibnedflapplication...

the drawings, the link comprises a line terminal I and a second terminal 9 in the form of a flexible cable or pigtail. Interconnectlng the line terminal I0 and flexible cable 9 are a plurality of fusible elements II, I and I4, the first of which is in the form of a helically coiled conductor having a longitudinally extending end III: at one end thereof connected to the line terminal Ill and a single turn Nb of reduced diameter at the other end thereof. This end turn is adapted to engage the flange I2a of a tubular metal conductor I2 in the form of a hollow rivet which extends well within the convolutions of the helically wound fusible element II, and is joined to this flange by means of a suitable solder connection indicated at I 3. The second fusible element I4 is in the form of a wire-like conductor having a serpentine end I4a serially connected to the fusible element II through the tubular conductor I2, and the third fusible element I5, which latter element is in the form of a meltable solder filling the space within the tubular conductor I2 not occupied by the serpentine end I4a of the fusible element I4 and joining the fusible elements II and I4.

At its opposite end, the fusible element I4 is connected to the flexible cable 9 as indicated at I6. Thus the circuit between the line terminal I0 and the flexible cable 9 is completed through the three serially related fusible elements H, I4 and I5. The fuse link of Fig. 1 also includes suitable housing elements as well as a shunt surge gap arrangement which form no part of the present invention and hence are not described herein. These elements are fully disclosed in the above-mentioned copending application.

Helically coiled fusible element II surrounds a suitable insulating tube I'l, one end of which engages the end turn III) of reduced diameter of the fusible element II. Preferably the tube I! is formed of a suitable ceramic or the like. The present invention is particularly concerned with the method of manufacturing the sub-assembly including fusible elements II, I4 and I5, the tubular conducting member I2 and the ceramic tube I'I. Specifically, the present simple and inexpensive method of constructing this sub-assembly has been found greatly to reduce the manufacturing cost as well as the time of manufacture of a fuse link of the type disclosed in Fig. 1.

In accordance with the present invention a fusible element I4 having a serpentine end I4a is inserted within a ceramic tube I8 which acts as a manipulating means and which is preferably a tube identical with the insulating tube I1. It should be understood that in manufacturing the fuse link of Fig. 1 it is necessary to employ insulating tubes I1 in quantity, and accordingly the manipulatin means I8 may comprise any selected one of these tubes. In Fig. 2 of the drawings there is clearly illustrated the first step in the manufacturing process, namely the step of placing the manipulating means I8 around the fusible element I4 adjacent the end I 4a of serpentine configuration. The next step in the manufacturing process consists in inserting the serpentine end I4a of the fusible element I4 into a tubular conducting element I2 until the flanged end I'm thereof engages manipulating means I8 in the manner clearly shown in Fig. 3 of the drawings. Preferably the conductive tubular members I2 are formed of brass, the reason for which will become apparent as the following description proceeds. The next step in the process consists in pushing the open, unflanged end of the tubular conducting member I2 into a paste solder flux while in an unheated condition so that the hollow space within the conductor I2 is filled with this flux as is indicated at I9 in Fig. 3. The flux I9 serves to hold the tubular conductor I2 on the end of the fusible element I4. By finger manipulation of manipulating means I8 relative to the fusible element I4, the desired degree of telescopic overlap between the tubular conductor I2 and the serpentine end Ma of fusible element I4 can be readily obtained. When the desired degree of telescopic overlap is obtained, the fusible element I4 and manipulating means I8 are manually held against relative longitudinal movement.

The next step in the process consists in so positioning the assembly shown in Fig. 3 of the drawings that manipulating means I8 engages the rounded upper edge 29a of a solder pot 20 filled or substantially filled with molten solder 2| which is maintained in that condition by suitable heating means generally indicated at 22. The specific gravity of the molten solder 22 should be considerably higher than the specific gravity of the tubular member I2, the reason for which will become apparent from the following description.

After the above-described steps are completed,

the manipulating means I8 is pivoted about the rounded edge 20a of the solder pot 20 in order completely to immerse the rivet or tubular conductor I2 in the solder 2| in the manner shown in Fig. 5 of the drawings. Incident to this step,

- the serpentine end Ma of the fusible element I4 is immersed in the solder, the interior of the conductor I2 is filled up with solder Which displaces the solder paste, and a solder film is formed on all of the external surfaces of the conductor I2. Since the solder has a specific gravity considerably higher than the specific gravity of the conductor I2, the tubular conductor I2 floats in the solder bath and consequently cannot fall from the end of fusible elements It to the bottom of the solder bath. This is an important feature of the present invention since it eliminates the necessity for in any way supporting the conductor I2 during the described solder immersion step.

After immersion in this solder bath in the manner just described, the fusible element I4 and the tubular conductor I2 are rocked or pivoted by means of the manipulating means I8 about the rounded edge 29a of solder pot 29 back to the position shown in Fig. 4 of the drawings. Capillary attraction prevents the molten solder filling the tubular conductor I2 from running out the ends of this conductor and causes an excess of solder to remain on the external surfaces of the conductor at the junction between the flange I Za and the tube portion of the conductor.

As a separate operation, a ceramic tubular member I! is inserted in a helically coiled fusible element I I in the manner shown in Fig. 6 of the drawings, so that the end of the tube II engages the end turn Ila having a diameter somewhat smaller than the diameter of the tube I1. Before or after this assembly step, the end turn III) of the coiled conductor II is dipped in a solder flux bath or paste. Immediately after the fusible element I4 and tubular conductor I2 have been removed from the solder bath, the component assembly comprising the ceramic tube I1 and the fusible element II is telescoped over the end of the tubular conductor I2 in the manner clearly shown by Fig. '7 of the drawings, to bring the flange I2a of the tubular conductor I2 into engagement with the small diameter end turn IIb and to telescope the tubular conductor I2 within the ceramic tube 11. As the end turn III; is

apogee-'4 'moized;:against' the flange I211; it: becomes inrmersed inthezsolder excessaccumulated at the juncture betweemthis flange and the. tubular portion .of the conductor l2. Pressure is now applied. through manipulating means l8. and ceramic :tubel'i tightly to .press the :end turn I lb of the fusible element ll against the flange [2a of the tubular conductor l2. The solder is permitted 'to cool to produce the desired internal solder union it between the fusible element. l4 and tubular conductor I2, and the desired ex.- ternal solder union [3 between the small diameter end turn Ilb of the. fusible element llv and the flange E2! of the tubular conductor l2. The manipulating means is is now removed and the subea-ssembly indicated generally at. 23 in Fig. 7 of; the'drawings is readyto be incorporated in a fuse link of the character shown in Fig. 1 of the drawings, in the manner described in thecopendingapplication referred to above.

Bypracticing the process described above, the cost:of manufacturing the fusible element assembly is'reducedto a fraction of its cost when manufactured by prior art methods. Not only is: the ultimate cost of the fuse link greatly reduced by employing this improved process, but in addition, a substantial saving in manufacturing timeis effected and the resultant product is more satisfactory due to greater uniformity in the character of the solder union l5 produced by this method.

It should be understood that the present invention is not limited to the particular process disclosed and described'in detail above and that changes and modifications may occur to those skilled in the art without departing from the spirit and scope of the present invention. It is, therefore, aimed in the appended-claims to cover all such changes and modifications.

I claim:

1:. In: the manufacture of fuse links, the method of forming a fusible solder connection between a tubular conducting member and a wire lilre conducting element to provide a fuse link.- sub-assembly, which comprises inserting an end of. said element within said member, placing a tube around said element to aid in manipulating said element to a desired position relative to said member, placing said tube against the upper edge of a solder pot containing molten fusible solder having'a specific gravity greater than that of said'memb'er, and pivoting said tube about said edge-toimmerse said member and the inserted end of-said element in said solder, thereby toform' a solder connection between said member and said element.

2-. In the manufacture of fuse links, the method of forming a fusible solder connection between atubular' conducting member and a wire-like conducting element to provide a fuse link sub-assembly, which comprises inserting an end of said element Within said member, placing a tube around said element to aid in manipulatin said element to a desired position relative to said member, placing said tube against the upper edge of. a solder pot containing molten solder having a, specific gravity greater than that of said member, and pivoting said tube about said edge to immerse said member and the inserted end'of said element in said solder, thereby to form a solder connection between said member and said element, said member tending tofioat'in said moltem solder when immersed therein wh'erebyit is maintained in engagement with said tube.

3. In the manufacture of fuse links, the method of forminga fusible solder connection between a tubular conducting member and. a wire-like conducting element to provide a fuse link subassembly, which comprises inserting an endof said element within said member, placing a tube around said element to aid in manipulating said element to a desired position relative to said member, moving said tube to provide the desired telescopic overlap between said member and said-element,-' inserting the end of said member into a paste solder flux to fill the same therewith,placing said tube against the upper edge of a solder pot containing molten solder having aspecific gravity greater than that of said member, and pivoting "said tube about said edge to immerse said member in said solder, thereby to form a solder connection between said member and said element by filling said tubular member with solder except for the space occupied by said element.

4. In the manufacture of fuse links, the method of forming a fusible solder connection between a tubular conducting member and an end of a wirelike conducting element to provide a fuse sub-assembly, which comprises telescoping the end of said element into said conducting member, and immersing said member and'thetelesoopedend of said element in molten solder having a specific gravity greater than that of saidmember while holding only said element, whereby said member tends to float and thus maintains its telescopic relationship with said element.

5. In the manufacture of fuse links, the method of forming a fusible solder connection between a tubular conducting member and a second con-- ducting member to provide a fuse link sub-assembly, which comprises arranging said members to-have-a predetermined telescopic overlap, and holding only one of said members while pivoting said members about the upper edge of a solder pot containing molten solder having a specific gravity greater than'that of at least one of said members, whereby the telescoped portions of said members are held immersed in. said solder by holding only said one of said members while the other member floats in said solder.

6'. In the manufacture of fuse links, he method of forming a fusible solder connection between a tubular conducting member and a second conducting member to provide a fuse link sub-asasembly, which comprises arranging mem bers with a predetermined telescopic overlap, placing a tube around said wire-like member to act as manipulating means to control said telescopic overlap, pivoting said tube about the upper edge of a solder pot containing molten solder having a specific gravity greater than that of said tubular member so that the telescoped portions of said members are immersed in said solder and said tubular member is filled with solder except for the space occupied by said wire-like member, said tubular member floating in said solder so as to remain in position relative to said wire-like member, and pivoting said tube about said edge to remove said members from said solder.

'7'. In the manufacture of fuse links, the method of' forming a fusible solder connection between a hollow rivet and a wire-like conducting element to provide a fuse link sub-assembly, which comprises inserting an end of said element within said rivet, placing an insulating tube around said element'to engage the head of said rivet and act as manipulating means to position said element relative to said' rivet, pivoting said tube against the upper edge of a solder pot containing molten solder having a specific gravity greater 7 than that of said rivet so that said rivet is floated in said solder, whereby the relative positions of said rivet and element can be controlled solely by movement of said element, and removing said rivet and element from said solder after said rivet is filled with solder except for the space occupied by said element.

8. In the manufacture of fuse links, the method of forming a fusible solder connection between a hollow rivet and a wire-like conducting element having a serpentine end to provide a fuse link sub-assembly, which comprises inserting said serpentine end within said rivet, placing an insulating tube around said element to engage the head of said rivet and act as manipulating means to position said element relative to said rivet, inserting the end of said rivet into a paste solder flux to fill the same therewith, pivoting said tube against the upper edge of a solder pot containing molten solder having a specific gravity greater than that of said rivet so that said rivet is floated in said solder, whereby the relative positions of said rivet and element can be controlled solely by movement of said element, and removing said rivet and element from said solder after said rivet is filled with solder except for the space occupied by said serpentine end.

9. In the manufacture of fuse links, the method of forming a fusible solder connection between a fusible member and a hollow rivet member to provide a fuse link sub-assembly, which comprises arranging said members to have a predetermined telescopic overlap, placing an insulating tube around said fusible member in engagement with the head of said rivet member to act as manipulating means to control said telescopic overlap, and pivoting said tube about the upper edge of a solder pot containing molten solder having a specific gravity greater than that of said rivet member so that the telescoped portions of said members are held immersed in said solder by holding only said tube and said fusible member while the rivet member floats in said solder.

10. In the manufacture of fuse links, the method of making a fusible element assembly which comprises the steps of placing a fusible element having a serpentine end within a tubular insulating member which acts as a manipulating means, inserting the serpentine end of said fusible element within a tubular conductor having a flanged end so that the flanged end engages said manipulating means, inserting the unflanged end of said conductor into a paste solder flux to surround said serpentine end of said fusible element and position the same within said tubular con ductor, placing said manipulating means on the rounded upper edge of a solder pot containing a molten solder having a specific gravity substantially greater than the specific gravity of said tubular conductor, pivoting said manipulating means about said rounded edge of said solder pot so that said unflanged end of said tubular conductor is immersed in said solder but floats therein so as to remain in engagement with said manipulating means which is moved to give the desired overlap between said tubular conductor and said serpentine end of said fusible element, pivoting said manipulating means about said solder pot edge to remove said tubular conductor from said solder, constructing a sub-assembly comprising a second tubular insulating member inserted within a helically wound heater coil having one end turn of reduced radius engaging the end of said second insulating member, inserting the unflanged end of said tubular conductor before the solder associated therewith has hardened into the tubular insulating member of said sub-assembly so said one end turn is soldered to the flanged end of said tubular conductor while the solder in said tubular member connects it with said fusible element, and removing said manipulating means from said fusible element.

11. In the manufacture of fuse links, the method of making a fusible element assembly which comprises the steps of placing a fusible element within a tubular insulating member which acts as a manipulating means, inserting the end of said fusible element within the hollow of a hollow tubular rivet so that the head of said rivet engages said manipulating means, placing said manipulating means on the upper edge of a solder pot containing a molten solder having a specific gravity substantially greater than the specific gravity of said rivet, pivoting said manipulating means about said edge so that said rivet is immersed in said solder but floats therein so the head thereof remains in engagement with said manipulating means which is moved relative to said fusible element to give the desired telescopic overlap between said rivet and said fusible element, pivoting said manipulating means about said edge to remove said rivet from said solder, constructing a sub-assembly comprising a second tubular insulating member inserted within a helically wound heater coil having one end turn of reduced diameter engaging the end of said second insulating member, inserting the end of said rivet before the solder associated therewith has hardened into the tubular insulating member of said sub-assembly so said one end turn is soldered to said head of said rivet and said fusible element is embedded in the solder contained in said hollow rivet, and removing said manipulating means from said fusible element.

12. In the manufacture of fuse links, the method of making a fusible element assembly which comprises the steps of arranging a wirelike fusible element and a hollow tubular rivet so as to have a predetermined telescopic overlap, pivoting said element and rivet about the upper edge of a solder pot containing molten solder having a specific gravity greater than that of said rivet so that the telescoped portions of said element and rivet are immersed in said solder, by holding only said element while said rivet floats in said solder, constructing a subassembly comprising a tubular insulating member inserted within a helically wound heater coil having an end turn of reduced diameter engaging the end of said insulating member, and inserting the end of said rivet while the solder associated therewith is still soft into said tubular insulating member so said one end turn is soldered to the head of said rivet and the solder in said rivet unites it with said fusible element.

JOHN L. YONKERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,702,234 Goodridge Feb. 12, 1929 1,783,642 Fergusen et al Dec. 2, 1930 2,293,455 Disch et al. Aug. 18, 1942 

